Elliot over at AustinOnTwoWheels.org put his neighbor's MADSEN through some paces and offers some insights:

I decided to jump in all the way and loaded up both my kids and Courtney’s daughter, Freya, for a longer ride around the neighborhood. The Madsen Bucket did not disappoint. It remained stable from slow to quicker speeds, and I felt little instability when the children shifted around. The lower center of gravity of passengers plus its more secure seating make this a better design for hauling people and kids especially than the Xtracycle.

Thanks for the thoughtful review Elliot!